Most times this occurs, it's one of two problems. The first is that the phone system is not generating DTMF digits. It should be very simple to verify this. Hope that your vendor shows up with a T-Berd or other T1 testing device that can record DTMF tones. The last several problems I've had are not tones. For example, we had to change a setting on a Samsung to ISDN PROGCON ON, and it started working. The second problem is harder to find, and that is answer supervision. If there is a local carrier between you and the LD switch, and you know that you are generating tones on the circuit, this may be the problem. Some switches are setup to only allow two way conversation after a far end answer supervision. This is to prevent unbilled toll calls. By default, the switches will allow talk path to the initiator of the call (ie, you), but not talk path in the other direction. Hence, you hear the AC prompt tone, but they don't "hear" your DTMF response. Harder to troubleshoot as you have to find someone in the Local CO who understands this concept and can correct it. There are other possibilities, but these are the major ones. Good Luck!
